To create a new database and a new user with a password in PostgreSQL on Ubuntu Server, you can follow these steps:

1. Install PostgreSQL if it's not already installed:

sudo apt update
sudo apt install postgresql postgresql-contrib

2. Switch to the postgres user:

sudo -i -u postgres

3. Access the PostgreSQL prompt:

psql

4. Create a new database:

CREATE DATABASE mydatabase;

5. Create a new user and set a password:

CREATE USER myuser WITH PASSWORD 'mypassword';

Replace myuser with your desired username and mypassword with your desired password.

6. Grant privileges on the database to the user:

GRANT ALL PRIVILEGES ON DATABASE mydatabase TO myuser;

7. Exit the PostgreSQL prompt:

\q

8. Exit from the postgres user:

exit

That's it! You've now created a new database and a new user with a password in PostgreSQL on your Ubuntu Server.